Display screen or portion thereof with transitional graphical user interface



FIG. 1 is a front view of a first image in a sequence of a display screen with transitional graphical user interface; and,

FIG. 2 is a front view of a second image in a sequence of a display screen with transitional graphical user interface.

The broken lines in FIGS. 1 and 2 illustrate portions of a display screen with transitional graphical user interface and form no part of the claimed design. The perimeter of the graphical user interface shown is understood to be congruent with an underlying display screen or portion thereof.

The appearance of the transitional image sequentially transitions between images shown in FIGS. 1 and 2. The process or period in which one image transitions to another image forms no part of the claimed design. 

CLAIM We claim the ornamental design for a display screen or portion thereof with transitional graphical user interface, as shown and described. 